Categories

Categories

Navigating the Maps

On the maps clicking on an individual icon will open a small popup tag inside the map frame giving the detail information for that quake.
Once you have finished reading that tag you can simply click in the background map to close that tag and select another if you wish.
You can also move the map around inside the frame by clicking and holding down the left button of your mouse on the map itself, rather than having to use the up/down/left and right arrows.

You can see the earthquake maps in various versions, ie map, satellite, terrain and even Google Earth.

At the bottom of each map is text saying "see larger map". This will open a new page with the same map, but with the icons and magnitudes also as a list. The list is in a ascending time order. You can click on an icon on the map or a magnitude number on the list and a detail balloon (tag) will pop up on the map from the location of the event.

Map key

On the maps each coloured dot orb or marker represents an earthquake, the colours indicate the size range.
Moderate = 5.0-5.9
Strong = 6.0-6.9
Very Strong = 7.0-7.9
Major = 8.0-8.9
Great = 9.0+
The data shows Mw (Moment Magnitude) as the main magnitude type where this is available, where this is not available another type may be used if it is above 6.5, all types are marked on the popup tags if they are available.
Some events have brief background information about the earthquake, damage, intensity etc, on the popup balloon.
The info is sourced from Historic World Earthquakes and Earthquakes with 1,000 or More Deaths since 1900 both USGS sites and Historic NZ Earthquakes, and Historic Tsunami and Volcanic eruption records

The sources are not marked, to save space on the tags.

The link below explains the types of magnitudes used. Where Unk: is used this mean the type of magnitude from the reporting source is unknown.Types of Magnitude

TIME

The days and hours, minutes and seconds posted in this blog in the text files and the popup tags on the maps are UTC time. This standard is "coordinated universal time", abbreviated UTC. This was formerly known as Greenwich mean time (GMT) Greenwich mean time was based upon the time at the zero degree meridian that crossed through Greenwich, England. GMT became a world time and date standard because it was used by Britain's Royal Navy and merchant fleet during the nineteenth century. Today, UTC uses precise atomic clocks, shortwave time signals, and satellites to ensure that UTC remains a reliable, accurate standard for scientific and navigational purposes.
Where UTC is not used it is noted as "local" time. Mostly older Chinese and Japanese events

Data Sources

The Data used to create the Maps is primarily from USGS/NEIC [usgs], [neic] and NOAA which back until 2004 is cross referenced with Geofon [geofon] and EMSC [emsc] Networks.
1940-2004 the main cross referencing used is ANSS and local networks such as Geonet of New Zealand [geonet].
Recent discoveries of other databases such as Instidudo de Geofisica del Peru [cndg], and Dept. de Geofisica, U of Chile [dgfudc]and iiee, the latter containing a vast amount of work done by Dr. Tokuji Utsu, Professor Emeritus of Tokyo University, lists containing more than 10,000 destructive earthquakes in the world from 3000 B.C. are all helping with the cross-referencing and also adding more events to the totals.

As well as the above main sources, the maps and lists show some events containing magnitude and location details referenced from the following catalogues used to complie the Centennial Earthquake Catalog 1900-1999 by
[ehb] Engdahl, E.R., and A. Villaseñor (2002);
[abe] Catalogue of large earthquakes 1897-1980 (1981,1984) and Abe and Noguchi (1983).
[b&d]Catalogue of large earthquakes 1897-1977, Bath and Duda (1979)
[brk] Magnitudes reported by the Seisomographic Station, University of Califonia, Berkley, USA.
[bji] Catalogue of hypocenters and magnitudes, State Seismological Bureau, Beijing, China.
[g&r] Catalogue of hypocenters and magnitudes 1904-1952, Gutenberg and Richter (1954)
[isc] Hypocenters and magnitudes from bulletins by International Seismological Centre, Newbury, UK (1964-1998)
[iss] International Seismological Summary (1918-1963). Also British Asssociation for the advancement of Science bulletins (1913-1917)
[jma] Catalogue of hypocenters and magnitudes1926-present Japan Meteorological Agency, Tokyo, Japan.
[mos] Catalog of earthquakes in the former USSR 1950-1961
[p&s] Catalog of worldwide earthquakes with Ms 7.0> 1900-1989 Pacheco and Sykes (1992)
[pas] Magnitudes reported by California University of Technology, Pasadena, USA.
[rothe] Catalog of worldwide earthquakes with Mag5.5> 1953-1965, Rothe (1969)
[utsu] Catalogue of earthquakes in the Japan region 1885-1925 Utsu (1979,1982)

Clicking on this icon under each map will open a text document list, in another tab (or window in IE), with the raw data the maps and graphs were based on for that year. The highest magnitude is noted in the lists, regardless of type.

The data is processed using Excel and transfered to GPS Visualiser in csv format where a KML Google Earth file is created and then is transfered to Google Maps and an interactive i-frame map is produced.

Quake Intensity – MM

The Modified Mercalli scale is designed to describe the effects of an earthquake, at a given place, on natural features, on industrial installations and on human beings. The intensity differs from the magnitude, which is related to the energy released by an earthquake.The 1931 Modified Mercalli scale
Notes on MM are on some quake event pop tabs, either shown a eg IV, VI, X etc or MM4, MM6, MM10 etc